DETECTION OF ADULTERATION 47 



5 % solution of uranium acetate, shake well, al- 

 low to stand for five minutes and filter. To lo c.c. 

 of the clear filtrate (in the case of cream use the 

 total filtrate, which will be less than lo c.c.) add a 

 mixture of 2 c.c. saturated ammonium molyb- 

 date and 8 c.c. dilute hydrochloric acid (i part 

 25% acid and 7 parts water), and place in a 

 water-bath at a temperature of 80° for five minutes. 

 If the sample contains sugar the solution will 

 have a prussian blue tint. This should always 

 be compared in a colorimeter with the standard 

 Prussian blue solution prepared by adding a few 

 drops of potassium ferrocyanid and 5 drops of 

 10% hydrochloric acid to a solution of i c.c. of 

 0.1% ferric chlorid in 20 c.c of water. 



It has been claimed that pure milk will give 

 this test. Occasionally samples of pure milk wUl 

 give a pale blue, but this can be entirely removed 

 by filtration, and the filtrate will be green; while 

 the color due to sucrose will pass through the 

 filter, giving the blue solution characteristic of 

 adulterated samples. The color is due to re- 

 duction of molybdic acid, and is caused by 

 levulose and dextrose as well as by sucrose. 

 Solutions of I gram of lactose, levulose, dextrose 

 and sucrose in 35 c.c of water were used in com- 

 paring the amount of color produced when heated 

 with the molybdenum reagent for five minutes. 

 Lactose produced no color, levulose gave a heavy 



